Swift on Mac OS 9

It also dates from the days when only one program could run at a time; because of that, even the latest version uses cooperative multitasking to run multiple programs–that is, a program has to yield its time to let others run.

Mac OS X was a huge step forward from Mac OS 9 in a number of ways, including preemptive multitasking so that you could actually run multiple things at once.

The Mac’s first high-level programming language was Pascal, not C! As such, the default format for strings throughout the Toolbox APIs was Pascal strings (a length byte followed by string data) rather than C strings (string data followed by a null byte).